US2433577A - Remote motion reproducing means - Google Patents

Description

Dec. 30, 1947. F. M. POOLE REMOTE MOTION REPRODUCING MEANS 2 Sheets-Sheet l Filed July 14, 1944 Patented Dec. 30, 1947 UNITED STATES PATENT OFFICE REMOTE MOTION REPRODUCING MEANS Foster M. Poole, Dallas, Tex. Application July 14, 1944, Serial No. 544,946

(Cl. i3-209) 12 Claims. 1

This invention relates to remote means for exteriorly proportionately reproducing a sequence of positions of a primary device which is movable in a closed container, and with regard to certain more specific features, to mechanical remotereading fluid flow meters or liquid level devices. Among the several objects of the invention may be noted the provision of said remote means for exteriorly proportionately reproducing a sequence of positions of a primary device which is movable in a closed vessel, without .the use of packing glands or seals engaging any movable part passing through the vessel; the provision of an accurate mechanical meter of the float type with which remote indications of float levels may be obtained and hence of the quantities represented by the float levels, as for example rate of ow in the case of a so-called rotameter liow meter; the provision of apparatus of the class described which sensitively enough, but without substantial hunting, responds to a float level change without substantially resisting that change; the provision in apparatus of the class described of a mechanical detector and transmitter means for determining and indicating float positions without any substantial interference from friction and without leakage difficulties; and the provision of a device of the class described which is simple, safe and reliable, requiring no electrical connections which are: a hazard in many applications such as in the oil field equipment. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of lthe application of which will be indicated in the following claims.

In the accompanying drawings, in which is illustrated one of various possible embodiments of the invention,

Fig. 1 is a vertical section showing certain flow meter and transmitter components of the invention;

Fig. 2 is a Vertical section showing said transmitter components and pilot valve relay components of the invention;

Fig. 3 is a. horizontal section taken on line 3-3 of Fig. 2 and,

Fig. 4 is an enlarged schematic layout of the invention.

Similar reference characters indicate correspending parts throughout the several views of the drawings.

Referring now more particularly to Fig. 1, numeral I indicates a lower header and 3 an upper header of a flow meter unit. Header I has an inlet 5 and header 3 an outlet 1 for connection into a uid line, .the flow in which is to be measured. The headers I and 3 are joined by spacing pillars 9. Between the headers is located a conical tube II having its small end downward and attached to header I by means of a stufling box I3. The larger upper end of the tube II is held to the upper header 3 by means of a stuii'ing box I5. The glands of stufling boxes I3 and I5 are adjusted by means of nuts I1 carried on the spacing pillars 9,

At numeral I9 is shown in general a oat having a main body portion 2I and a vane 23.

The elements thus far described operate in the line of ow being measured by admitting fluid at the inlet 5 and discharging it at 1. The fluid in passing through the .tube II tends to move the fioat I9 upward. The specific gravity of the oat is greater than that of the fluid being measured so that it Atends to sink down, but it is pushed up by the force of the uid rushing through the tube II and around the vane, until a point is reached along the taper of said tube I I that the clearance between the noat and the tube wall involves an upward force which equilibrates the float. There is a point of equilibrium of the oat for each rate of flow through the tube II. The greater the flow, the higher will be the point of equilibrium and vice versa.

The position of the oat I9 is visible if the tube II is made of a transparent material such as glass. The glass may be calibrated in units of volume per unit of time (gallons per minute for example). This is usually the case but a disadvantage of the construction is that its readings can only be taken at the location of the flowy meter parts per se. The present invention provides means for transmitting to a distant instrument information regarding the location of the oat and continuously recording it. The distant instrument is calibrated in terms of the flow through the iiow meter parts.

Heads 25 and 21 attached respectively to the headers I and 3 carry stufling boxes 29 and 3| respectively. These hold in place, without leakage, ya guide tube 33. Around the guide tube, adjacent the heads 25 and 21 are tubular stops 35 and 31 respectively threaded into the heads 25 and`21. The iloat I9 is made cylindric and or release:Y port .43;.uponwhieh a steel'ball check."

45 tends to rest; At its lower endthe tube 39-is attached to a piston rod 41 extending from a piston 4S. The piston rod 41 has a free slidingr` nt in a cylinder 5l which is. carriedcuponthe.`

nipple 4I. A passage 53 in the piston rod 41 forms the communication between the tube39-f and the space 52 above the piston 45.1. This .space3 is enclosed by the cylinder 55 (in which the piston 49 operates) and a head -51 on said cylinder 55.` A.l

gauge 59 registers pressure in the space 52 above the piston49; Pressure-isintroducedinto this space through a branch line 6I leading frornfa;

mainfair line.-63 In5the airflineeIiBgis -apressure regulatorV and lter unitl 65.- Thebranch line 6I feeds the-cylinders through ane adjustable needle Valve-.Glwhichacts yas a throttle.

The piston 49..:is Abiased.downwardfby pressure above it. Thisbias vat some point is equilibrated by means .oi aV compression, spring; 69 reacting. below -the .piston from an opposite enclosing head,

prise an Vimbeddedpermanent magneten, for eXeample ofthe rillnico.variety.A Since `the Yball 45 is magnetic, anymovernent of thefmagnet 12, as. determined by change in ilow through the meter,

tends tomove.with itv thelball I3-up vordown in the tube 33, Thusrif theoat I9, rises.in response to .increased flow, lthe .ball 45 .which .israisedby the magnet- 12. moves away from the seat 43 at the upper end of the tube 39.. Iii-.uncovering the. part 43 'theair pressurerabove.-thepiston 49n de. creases Vbecause the increasedleakage outof saidtube 3 9 occurs. i`aster thanair is .admittedthrough the restriction at need1e valve .61. The resulting decreased airl pressure alcmve.A the piston 49, as.:

sisted by thespring 59, causes piston 49 Qto rise, carrying `with .it the tube 3S'until thenew position ofjthe ball 45; isoVertaken by theseat 43. Equi.-

libriurn will then again v,be reacl'ied when the .ball 45and the seat 43are separatedbya very thin` iilm of continuouslyv escaping air which iinally. escapesffrorn theupper end of' ti 1 lg\e 3;i .v Equilib-- riumr'will-then also be established between the amountoi vented air and the air supplied through the restriction at E1;

Conversely; upon a decreased rate of ow through the tube'A II, float I9-descends and the; magnet 12 forces-the ball45 toward the seat 43. This causes the air pressure aboyepiston IS'to4 rise, thus pushing downthe piston 49.and tube 39 until equilibrium is re-established between the amountofventedlair and-the air supplied vwhich initurn equilibrates tube-39 with respect to the ball 45; Thus it will beiseen thatfor each position .of the oat: I8; there is acorrespondingposition :for the piston-:49,i because thefport '43 `always comes to rest in thesame relativelpositionwithV respect toY tl'iezfloat l9through the Vaction of the magnet 12 andball 45;: Thus :eachrate of iiowf determines a neu/position of 'thefloati Islwhichl is Aunimpaired-.by any coupled-mechanismr SinceAv thetulce` :ia-always: takes up the; same relative.4

position .Withrespectto thevfloatithere will occur a Ycorre spondir-igfolefinite position of l,the .piston V49; It is the intention to apply the force required to bring the piston into equilibrium to a pilot valve of a remote control air line. This is done by means of a long tension spring 13 which is hooked at its upper end in a hollow part 16 of the piston rod 41. This spring is hooked at its lower end to a clevis 15 attached to a transmission link 11. The link 11 is fastened to the upper enclosing head or diaphragm 19 of a flexible bellows 8l. This head 19 is biased downwardiby means of a spring 83 reactingat its upper endlagainst a xed ring 85. The ring is xed on the upper end of a.casing 81 which has an adjustable thread attachment Brito .theA head 1I of cylinder 55, The bellows 8| is sealedto the separating wall 89 which forms a part of the lower end of this housin g (Fig. 4),. A ,bleeder tube 9| extends through the wall 89-and`has its upper open end closely adjacent3to the under side of the diaphragm 19. Thus diaphragm 19, which is under control of spring 13 acts as variable tnrottlng, means for anyairfiowingrout of the. tube] The.p,ortion or the. casing81..b.elow the ,Wall .89 constitutes a.. diaphragm. type.. regulating.. pilot vali/eier c0ntrol1ine.,air pressure-in an air line.

I I5 leadingto. a receivingrecordingtindcator,I I1. Filtered andregulated air is 1lllliehi; tothisyalve over linelfV andinto a port 93; Someofthis, supply flows through a iixedjrestriction Vllitojfhe top cia-diaphragm 91; Thediaphragm chamber is indexedas a whole at99.' The top partjofj this chamber 99-(above the diaphragm .91) communicates Via passage IDIWith the insideofja; flexible bellowsul03'fastenedtothe bottom of casing -81- On `the -end'ofthe-exible be11o,Ws I03 .is albleeder valve-I5 cooperating with a bleeder port-.MJLV the ylattenbeing inafcompartment |119; also .fastened-*to the bottom ofcasing -81 and surrounding the bellowsllll:

Part ofV the -airsupplied` from pipe 63' passes through port HD2-t0 thelower-section Illil'ofjthe diaphragm` chamber-below the diaphragm 91'.' Valve I I Ixwhich controls port I 02 is attached-tothe diaphragmV 911' Valve. I I Iisbiased--shutbya; follower spring |84.; The-diaphragm 91 is-biased up ..by..a. spring I 2i When the-4 diaphragm -rises- Valvegl I I :closesand-vice-versa.

The v chamber I 051:; beneath theA diaphragm- S1'I is alsoeincommunication withthe inside o f thevv compartment ,I 0S, which lisetosaye outside-britnebellQWs |031; T he...connection.isshown-- at II3J1 This.;connection-` I I3ealso ,communicates-with anairfline; I i 5which transmitspressuretoI a recording indicatonl I1:` As=indicatedin Fig. 2lth'is is off therecoidingftype; although anonerecordingtype may; also be used.;v There is also acommunication I Nif-betweentneilinecl I fr-and the :inside-.of the :bellows 58h, Therecei-vingl recordingy indicator I I1:I has a -.clocl ,drivenjpaperysealeeand.iits recording; pen I 2 I responds; to. variationsyingpressure; in-.the line .I Hit Them force inthe.. tension spring 13 (as edeterf. mined by its deflection caused byI movement o fg piston 49) is appliedtothediaphragm 19..- This will hereinaiter Abe referredto, as the variablev to, be measured.` This Variable being proportional to thel displacement of the pistonlisg hence proportional to ,the displacementof the iloatj 9. Itishould be noted at this ppintthat' .the springr 13 is made as long asv possible sc that it.,h.s..-a linear characteristic relationship between force and deflection.

Reerringto Figsr 2-and3ethe left-hand pressure gauge 58 registers the air supply pressure entering:thefiregulatcreandfiilterwe It-may-be between 35 and 125 p. s. i. depending upon a users Filtered and regulated air flows from the supply pipe 63 and port 93 through the fixed restriction 95 to the top of the diaphragm 91 and then out through passage to the inside of the bellows |03, thus controlling the automatic bleed valve |05. Bellows |03 being of metallic spring type has a contractive bias toward an open condition of the valve |05. For weaker bellows |03 an auxiliary spring can be used beneath it, biasing it in a direction to open the valve |05. Some also flows out of orice 92 at the end of pipe 9 Some supply is also admitted through the valve to the underside of the diaphragm 91. This air through connection ||3 communicates with the inside of the chamber |09 (outside of the bellows |03), and also connects with the receiving meter ||1 through line ||5. It also passes in part to bellows 8| through passage I9.

When the piston 49 descends, the tension in spring 13 decreases proportionally. This is detected at the orifice 92 of the pipe 9| because of the closing action of the diaphragm head 19 under spring 83. This causes pressure to increase on the upper side of the diaphragm 91 and at the same time tends to close the automatic bleed valve |05. Air is also admitted through the then opened pilot valve I to the bottom of diaphragm 91 and outside of the bellows |03. The air admitted under diaphragm 91 equilibrates it in its original position. It also equilibrates the valve Conversely, if the piston 49 rises, more force is exerted by spring 13 tending to lift the bellows end 19. Pressure on the top of diaphragm 91 is ythus reduced and at the same time the automatic bleed valve is biased open to discharge more air from beneath the diaphargm 91 until a balance is again reached. The bellows end 19 in each case comes to rest at approximately the same distance as it was originally from the end of the tube 9|. Variable pressure is thus transmitted to the receiving meter and the regulator after each change equilibrates itself ready for the next activity.

It will be noted that the pressure on the top of the diaphragm 91 is always higher than that on the underside by the amount of force exerted by the loading spring |2| `and spring |04. This produces a differential pressure across the nozzle 92 at the end of the tube 9|. This differential is maintained throughout the entire range of transmitted pressures thus insuring a pneumatic balance at substantially the original positions of the regulator parts. The change in balance position of the bellows 8| between zero and full scale is less than .001 inch, thereby eliminating the effects of any non-linear characteristics of bellows 8|. This insures a transmitted pressure which is always in direct proportion to or linear with the measured variable (force in spring 13).

From the above it will be seen that an increase in pressure on the top of bellows 19 tends to decrease the gap at nozzle 92. thereby building up air pressure inside of the pipe 9| and area 99 above the diaphragm 91. This action tends to shut off the bleeder valve |05 and open the pilot valve The opening of the pilot valve in- 'I creases the air pressure in the area |00 beneath diaphragm 91 and also the pressure outside of the bellows |03 and inside of bellows 8|, thereby tending to restore the equilibrium which was upset by a change in pressure on the top of the bellows 19. When this equilibrium is re-established, pressure on top of the diaphragm 91 will be higher than the pressure below it by the amount of the pressure exerted by the springs |2| and |04. This differential pressure across bellows |03 is suiiicient to cause valve |05 to remain very slightly 01T its seat. Thus when the pressure on the top of the bellows 19 incipiently increases, the bleeder valve |05 will incipiently move toward closed position. Conversely, if the pressure on top of the bellows 19 is decreased, the valve |05 incipiently opens. The adjustment between valve |05 and its seat |01 is such that when the said diiferential pressure between the inside and the outside of the bellows |03 exists, the valve |05 is still slightly open.

Another condition to be noted is that the overall length of the spring 83 remains about the same under all conditions (within plus or minus .0005 inch. Therefore any non-linear characteristics of this necessarily short spring introduce n0 appreciable error. The relationship, for example, between the expansion spring 93 and the tension spring 13 is such that when the piston 49 is at the top of its travel the algebraic sum of the forces of compression spring 83 and tension spring 13 is equal to two pounds times 1.55 (which is the eiective area in inches of the bellows end 19). When the piston 49 is at the bottom of its travel, the algebraicsum of the forces of the expansion spring 83 and of the tension spring 13 is equal effect, inasmuch as the steel ball 45 with its ventV tube 39 will cause a rise or fall of the air pressure on top of the piston until the desired position of the vent tube 39 is reached. From this it is clear that any slight air leakage through the clearance between piston rod 41 and the extension 5| is immaterial as the air supply is continued until the vent tube 39 reaches its proper position with respect -`to the oat I9. Stated otherwise, spring 69 which has a large deliection requires no linear characteristics. Spring 83 does not deflect enough to make a linear characteristic necessary in its case. Only spring 13 requires a substantially linear characteristic and provision has been made for making this very long so that such a linear characteristic is practicable to obtain.

The bellows 8| and diaphragm 19 thereof may be referred to as a member responsive to the variable to be measured. This responsive member 19 is only slightly movable to bring about transmission of the desired effect throughpipe H5 to the recorder ||1. It is therefore of importance that the displacement which it is desired to measure of the piston 49 be converted into pressure changes through the lspring 13 for Iapplication to the rezwi??? i* l 7 851 snonsive; memberV 'me and; that; these.. pressures the.magneti12,isenottappreciably-distortedand? shouldbeaproportional to -the .piston disp1acement: haseits full effect .-upon-the'ball 45a This.1meansf;thata spring.,such,asf'lfmustfbe In.viewofthe-above,it-.will.beaseen that,thef rather-longginlorderzto-,obtain` a., lineariA forcee several objects fofthe invention .areachieved andi.. deflection relationshipjfor that springi. Sinceianygf- 5; otheradvantageousresultsattained.,

compression:springkthatiis made-Jonge; to. ,accom-g As ..many changes fcould. besmadetin -.the.fab'ovef` plish :this end isaxiallyunstablef the-sp rines-fi3;is.-y constructions v^Without departingtfrom. the. scope e providedasa. tension spring;Whicn-mayebemadee of? the-invention; Aits is y..int ended..that ,i all matter` asflcrlgsgasedesiredto obtain .the stated effect vv-ith-v containedfin. the; above! descripticnor shown .in t

olitfintroductionl of :any axial 'instability- 10. the accompanying drawings :shall be. interpreted Iman `exemplary embodimentoof theinvention; asaillustrativeTand,-notfin.-alimitingsensei the trayelwof the piston 49 isfabout' `inches.` Thel I claim:

maximum range-ofqmovementofra.float such 1.y Inapparatus-lof the fclassydescribed, aliuld I9iis1of theorderi-ofg-20 inches.-. 'I'hismeansthat:V chamber;`A hollovvay meansf passingf through= the, thesuppe-r endqof the. tube,r 39 moves througirfa-V 15k; chamber,- and .,thewfluidstherein, la. float, the Vele.A quarte-re,oit-.thezmaximumfrangefoctheoat; By: vation .offwhicn inthe. chamber: is changed. by, changing-l thef, lengthfoi thefftube 39, any.-.chosen the fluid.; andi being; movable alongsaid r hollowl quarter;-ostheioperating range-fofthefloat may-.l means;l a-tube in the-.-hol1ow.means;and extending, be registered;Y For-eXam-ple, it may, bewdesired .toy exteriorlm` therefrom-.and havingi an ..orice .nor.v record'v'the':lowerqtlarter offtheeoat range` in-:20,,mally; adjacent to'said-.floatgafmagnetic' checles` which;cas efa fA-shorter-- vent f tubef Sewouldbe ,1eme valve-g associated --Witl'if said. orice, a xmagnet' 011.; ployed.l If; itV were .desired to; recordthe upperi said;float'controllingJ the position-of;saidvalvee qua-rteri of the range',Y aglonge-rf tube :SSA- would `bei,` with ,respect to said .oriceromeansi for conveying; enfiployed;v Byiseleotingjtheproper length oftu'beair toisaidstube: toexhaustat saidorice, and 39 any quarter of the oat range would be re-.ggggoperating rheanS-m'V movingfthe-.tube which is: corded.; Thereason for thisisthat'the variations responsive Ato the pressure'v of said air, said'pres.-v ofthe iioat inthe example are not more than-one sure .f. being j determined by the .position of said.: Quarter of=themaximum ,floatfrange regardless;v valve .inrespeetto the-:orice.-.. offiwhether the rate offlow through the tube; II- 2. InI apparatus of :theclassdescribed,y auidi is.high.-or-lowv Obviouslyiifitwerc desired tofaochamber, hollow means.` Passing;v throughv thef record the entire range,` then; a stroke of Y equal chamber; and: the -uid therein, .aaoat; the elelength would-'need to be provided for thefpiston vation off'W-hich-fin. the. ohambereisechanged by.Y 49,*-it being understood that the device would needv the iiuid;,and beingi movable f along said hollow i* tolse.-re-dimensionedifonV such; a purpose..y Or, means; La' tube'v in :the.hol1ow:means.;andextend other fractionssof-thetotal rangegmightf be ref-35;;ing exteriorlytherefrom and-having anioricef. spondedrto.: normally; adjacent tosaid float; afmagnetic check: The `devieeis,.econon'lioal because-under equili-b'-,-Vy valve..fassociated; with said,4 oriiice,A vafinagnet on.; rium conditions-the` airconsuinption less than; sai-dyoat: controlling;therposition:of fsaidgvalve; .1 cubic foot offree air per minute,the'ball I3; with;respecttosaidjorice, ,substantiallyI throt allowinga'very thin lmto pass out of theoricemi tledmeans forconveying air to;said tube to .ex-.J at the top of the tube 382 Alsoxwiththe receiver. llaust` at .said zorice, andfoperating@"means fOr'V I I'l locatedat several hundredreet-distance from movinggtheftubewhich is:responsive:totheapres-aV the transmitter andconnected yWith 1/'4 inchinside.v sure of said air as determined by the position of diametertubing, the lag-between operation ofsthe" saidvalve in-respect to the .oriiceg oat I91and' ofthe indication onine-transmitters45 3: A liquid fiowfmeter: Comprising@ 'VeriiCa'liYf I 2 I -is not moreftha-na :fewV seconds.- For shorter: arranged'downwardly,-tapering. con-ical` 'tube ycardistancesit is 'lessa rying., asow; ofn liquid fupward, awhollow. guider One-.e1ement ofwthe jnventioneis the-meansrfor passing:coaxiallyythrough.saidtubeoaioat sure.: obtaining` exteriorly of the liquidi;'compartment or i rounding g and.: slid-ing;v on"` said#V guide; g a a magnetic". the flow-meter afmeasurablefvariablef;(positiorriD-imember; carried'zby Said' fltr-afmovabiertuberin. of ,pistonfdi which` changes in acdireottlinear; sa-idfguidefhaving*anaorificefadjacent..the-zfloat, proportion :to the,conditionuof;a-va1'iab1e within; awmagnetic Valve-baSBd1byvgIaVity towardiseat' the liquid.- chamber (positionaofv thenfioaeg ISL. ing oven said--aoricefia'cylindenfaspiston inzsaid.: The sameprinciple fcanibef used .imanalogous :ape cylinder, saidetube-.extending:fromrsaid':guide: andi paratusfor example, for-measuringqthelelevation.; sigbeingf: attached,- to, said: piston skandihavingf; com.v` of. @liquid 1eve1 floatthe p gsmon-m5Which-ds` munication with the part of the cylinder above;- pends not .upon liquid flow (as herein) f'butupon; ther-piston; ,anspring:biasingzsaidxpistonf upward, buoyancyvv of afloatwhichridesfon aliquidsur-z throttlinggmeansffor admitting airrtostheffcylirr-iface..4 In such caseythe float Yhas;aspecificgravity; der above:saidpistonforrzleakage from'saidiorice 'f which is less than thatoftheliquid. nogA asf-determined lby-ythe'.` position offsaid-.f-valvdf arr` In viewh. of the abovefit may-be seen-that-'zthe-,f air operated:indicating::receiverga` fluid circuit; invention has@applications-broader;than the/apeA connected WithfLsaid receiver for operating-ity.. plicationindicatedV bythe specific-device :shown: meansf [email protected] sx-for: controle f Forexampla. it mayalso beY -usedzto reproducein f. lingzlsaidaoircuit,.,andrresilient'imeans Vffor: a1op1y1-A a.- remote moving-'deviee a sequence of` .'positfonss ing;l variableoforce tto. saidiresponsive:meansninz: of any movableprimaryfdevice suchxasnin :an-:f substantiallyl direct proportionttorthe'fdisplacee orifice meter, area'meteronthelikes Als'dthe mentiof. said pistone.

action ofva dapper -ofach'eela valve or Athmttling@l 4; A-i-1iqui.d:flow..-meterfcomprising2.a.vertical1yr Valve ina yoherirlioal process mayzbefremotely re. arrangedfdownwardlyztaperinglconicalftubefcar-'- produced. The .remotelyfmovingdeviceneedgnoti 'mi-k ryingEaliiowfffiiqllidtupwardxa hollcvwg-uiizierpassfy be. onefthat simply moves asan indi-catorfbutimayx inggcoaxialiyfthroug-hsaidrtube; a fioatlsurrounde. beione. that has.operativepurposesV ing and sliding envasaidgilidenaimagneticfmemef It .will .bei understood :that i the :tube-.33 fisepref ber-f.carriembygysaidqfloat, 4,asmovabletubein-said erably. non-magnetic solthat `theencumal..formt-off; gnidehaving an oriiice:fadjaoenttheloateaemagef` the,magnetic.eldas..determinedebyethe-shapevof 375; neticevalyeebiasedwby gravityetowarduseatingeover:y

said oriiice, a cylinder, a piston in said cylinder, said movable tube extending from said guide and being attached to said piston and having communication with the part of the cylinder above the piston, a spring biasing said piston upward, substantially throttling means for admitting air above said piston for gradual leakage from said orice as determined by the position of said valve, an airoperated indicating receiver, afluid circuit connected with said receiver for operating it, means responsive to force for controlling said circuit, and resilient means for applying force to said responsive means in accordance with the displacement of said piston, said last-named means comprising an elongated tension spring connecting the piston with said responsive means. 5. In apparatus of the class described, a liquid chamber, a movable iioat in the chamber including a magnetic element, an air exhaust pipe having an orifice and along which pipe the float is movable, a magnetic valve member associated with said orifice adjacent which valve member said magnetic element is normally positioned, said exhaust pipe being freely movable and extending from the liquid chamber, a cylinder, a piston operating in said cylinder and being attached to and movable with said exhaust pipe,

said exhaust pipe communicating with the cylinder, an air supply connection with said cylinder on the side of the piston with which said exhaust pipe communicates and applying pressure thereto, means for throttling said air supply to supply air at a rate which is less than the maximum and the exhaust pipe are moved against the biasing means until said orice again takes up a normal position with respect to said magnetic valve member.

6. In apparatus of the class described, a liquid chamber, a movable oat in the chamber including a magnetic element, an air exhaust pipe having an orifice and along which the float is movable, a magnetic valve member associated with said orifice adjacent which said magnetic element is normally positioned, said exhaust pipe being freely movable and extending from the liquid chamber, a cylinder, a piston operating in said cylinder, said piston being attached to and movable with said exhaust pipe, said exhaust pipe communicating with the cylinder above the piston, an air supply connection with said cyl inder above the piston, means for throttling said air supply to supply air at a rate which isless than the maximum rate at which air may exhaust from said orifice, means biasing said piston and exhaust pipe upward whereby any incipient upward movement of the neat causes said magnetic valve member incipiently to open and temporarily reduce air pressure above said piston so that the biasing means lifts the orifice to a nor-I mal position with respect to said valve member and whereby when said oat descends said magnetic valve member incipiently closes the orice to effect rise in pressure above said piston whereby it and the exhaust pipe are depressed against the biasing means until said orice again takes up a normal position with respect to said magnetic valve member, a fluid operated measuring receiver, a fluid pipe extending thereto, pilot valve means connected with said iuid pipe and having a responsive member for actuating said pilot valve, said responsive member having only a slight degree of movement for substantial changes in force thereon, and spring means connecting said piston and said responsive member, said spring means having linear force-deflection characteristics whereby force is applied to said responsive member in proportion to the v'displacement of said piston.

'7. In apparatus of the class described, a liquid chamber, a movable oat in the chamber including a magnetic element, an air exhaust pipe having an orifice and` along which pipe the float is movable, a magnetic valve member associated with said orice adjacent which said magnetic element is normally positioned, said exhaust pipe being freely movable and extending from the liquid chamber, a cylinder, a piston operating-'in said cylinder being attached to and movable with said exhaust pipe, said exhaust pipe communicating with the cylinder above 'the piston, an air supply connection with said cylinder above the piston, means for throttling said air supply' to supply air at a rate which is less than the maximum rate at which air may exhaust from said exhaust pipe, means biasing said piston and exhaust pipe upward, whereby any incipient upward movement of the float causes said magnetic valve member incipiently to open and temporarily reduce-air pressure above said piston so that the biasing means lifts the orifice to a` normal position with respect to said valve member, whereby when said float descends said magnetic valve member incipiently closes the orice to effect rise in pressure above said piston whereby it and the exhaust pipe are depressed against the biasing means until said exhaust pipe again takes up a normal position with respect to said magnetic valve member, a fluid-operated measuring receiver, a uid pipe extending thereto, pilot valve means connected with said fluid pipe and having a responsive member for actuating said pilot valve, said responsive member having onlyv a slight degree of movement for substantial changes in force thereon, and spring means connecting said piston and said responsive member, said spring means having linear force-deflection characteristics whereby force is applied to said responsive member in proportion to the displacement of said piston, said spring member comprising a long tension spring.

8. A ow meter comprising a downwardly tapered conical chamber through which fluid flows upward, a xed 'hollow' pipe 'positioned vcoaxially withthe chamber and having 'a vent at the top, a iioat movablev to various elevations according to the amount' of flow through the chamber, movement of said oat being guided by ysaid pipe and the iioat being around the pipe, a magnet carried by the float, a freely movable tube in said pipe and projecting from the lower end of said pipe, said movable tube having an exhaust orice adjacent the float, a, magnetic ball valve adjacent ,-ihollowrmeansranfd extending therefromvandhav- 'i2 @as :iietermlned rby Svtemporary-oat 1f-movement, whereby the foperatingrmeanssaidjusts ',the'-` tube :tofthezvalvetocassumeiainormahpositiommeans responsive to a'variable :pressure f'formakng tensionsspring extending? fromzthe upperfend 120i ssaidmodsand throughzsaidrhollowi pistonfrodand fheingzfastenediat itsvoth'er enditosaidsmeasuring i'meansifor applying :afrol-.cee thereto proportional said z-rcsponsive means :comprising flan --elongate Ltensioni.springfhavingsubstantially lineare-'forcefiisplacementlcharacteristicsand connecting :said a-pi'ston :.'operatingf means with .fsaid .responsive @to :displacement tof f said `lpi'ston, ithrottled means 510 111182115.

rfor introducing sa; ow.: of fair: into =said cylinder above inthe irpiston.; adapted toi'build up `pressure above atl-ie :piston "when f' said valve approaches iizlosurezbutpotherwisetto'iallow ipressurey reduction,

:1 1. rnfapparatus :of the character described, a emembermovable torvarious :ipositions magnetic meansmovablei therewith,earconduitmountedf for movement foflowingfsaid member, onerendnofsaid the iioat cause opening andvfclosingmovement irespectiveiyf ssaid valve :iso f as respectively to freduce :orzincrease .pressure on A' said.. piston and :thereby respectively .to causef-saidf piston to;r-ise :meansfv andrh aving aan; .orieei thereinpatmagnetic i: vcheckv valve f memberatassociated :Withfasaid :,orice, klxsaid. :checkVv valve rmemberlbeingdispnsed Within IAthe magneticriieldxof saidrmagnetirrmeans, means or deseend eComm-g gto upward ,Ur :dOWnWaI-d 420 ffor :conveying air` i tosaid :conduit fto'iexhaustfat movements-5 respectively/ of-'zsaid fiioat, the I-'piston aand-fioatrmovementscbeinglinearly-proportional.

'.Qilmapiaratusfoi-ltheplassfdescribed; arf-chamfjaericarrymgfiuidtto be: measured; a hollow mea-ns v.'said` oriiice,-=..andfoperating;meansgffor.;movngzthe ygconduit rwhichlisqresponsivef to tithe pressure lbf .fsaidtainf said :pressure being :ideterminedz by'gthe yposition# offsaid:A check; valveimenibeninrespectto ,thereim .ma foat, cthe faelevation for which 1in .the chamber iszchangedby theuidiandfbeing moveable .alongsaid rhoilowirmeans, a tube :sin the .ginangoce imthefhllow:meansnormal-ly'adia- 4cent borsa-riff!oat, a magnetiofcheck valvevassoaciated withffsaid f orice, a magnet fionfsaid loat :controllingithe-fposition:ofisaidzvalvewith)respect Y)to thev oricenthrottlingrmeansforfconveyingfair gffto-zsad' tube ztojze'xhaust .eat :saidforica piston' loperating` means `'Jior 'y moving the tube which is .fresponsivertoithefpressureoffsaidi air,r\said= pressure lbeing :determined :ibyi-the itemporary 2 move- ,vment -eofrsaidvalve fin Airespect#itolt-he oriiieeas .ydcterminedzby .temporaryoat movement, wherebyetheppenating;meanssadjustsftheftubefto'fthe ivalveito:assuneiafnormal position theretmeans #responsive tof-asvariablefpressure formak-ingan 1-2. ln apparatus sof z-the Vcharacter Jdescribed, sa. vertically movable :member V:hav-inge magnet Jthereon, -a @vertically :movable V-itube :having its :,fupperzend :Vfadjacentsaid'magneti and having-ian :30 orifice thereinlrand af-valvecfseat f thereon; means .forlsupplying air;- under gpressuretrofssaid tube; a rcheckvalves-member:associatedwith said :orice :and ;said valvesean:fsaid `;check @valve member yfcomprisingffazball;.of magnetic-material vgravity- .,lwithin: the fmagnetic v ;eldrofrsaid magneafsaid VVfair:exhausting ythroughi-sai'd oriiiceuandzitspressure f being determined fby the :position :of -tsaid iball :with Vrespect; :to fthe aforice @and `valve kf seat,

@'40 aand-fmcans L:for :moving-said :tubetto:-foHovvrsaid v.movab1e-;memberfin"l responsertoffvariation :ofY the t; pressure of fair .in=.said:;tube: causedfby:v movement 1. of f said bail :relative: to said. tube .nY in accordance swithmovement: of 3-said'verticallv'; movable .finemiindicatiortrand rmeans connectingsaidf piston and mame:

rsaid responsivemeans :comprising 4`an elongate (spring having esubstantial'ly 'f linear :Torce-:dislgplacernent characteristics land Aconnecting `said ygpiston @operating fmeans with said freSDOnSl/e -inathehamberiscchangedshyatheiluidiand being v55 Vilrlovable esa/long` saidyhollow amelans, :aitubeY lin: the

holiowgmeanszandiextending therefromz-andhavlng-r :aneoriiie ein @thefhollow means normally liardjacent to said float, a magneticfcheckzavalve1as- ,controlling liegA position ofgvsaid wahre 'with-rev: orfce, gthrottling znficansV for icon- `Iveiling:-A air v-tossaid .tube ,ltoiexhaustifatssaidzorice, stomoperatingmeansffonmovingithetubepwhich .;pressure-beine u.determined eby @the -itempoiarv movement-nissan .valvefin` -respectf-to'theioriee :FOSTER rM. fPOOLE.

` :REFERENCES GITED QUNITED STATES :PATENTS 2' Name .f Date Moore Feb: 23, 1943

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